The present invention relates to a reel disc device for use in a recording and/or reproducing apparatus and more particularly to a reel disc apparatus which can be controlled in accordance with fluctuations in tape-tension both in normal recording and reproducing mode where the tape runs in the normal direction and in a reverse reproducing mode where the tape runs in the reverse direction.
There have been developed apparatuses for recording and reproducing video signals on or from a magnetic tape which have a mode of operation which permits editing of the recorded tape. Apparatuses of this type have the ordinary functions in which the tape travels in the normal direction at a predetermined speed for recording or reproducing operation an another function in which the tape travels in the reverse direction at a predetermined speed for reproducing operation. This reverse reproducing operation is used in the process of editing the recorded tape in order to locate the place on a tape where a specific video signal has been recorded. In the reverse reproducing mode, the tension of the tape running in the reverse direction must be controlled as it is in the normal recording and/or reproducing mode.
The supply-side reel disc assembly and the tension servo mechanism in ordinary recording/reproducing apparatuses are constructed with a brake band which is connected to a tension lever and surrounds a disc with which the reel is engaged. This mechanical tension servo mechanism is generally adapted to operate normally only when the aforementioned disc rotates in a predetermined direction. In the reverse reproducing operation, however, this disc must rotate in the direction opposite the predetermined direction in which the servo-mechanism operates normally and, consequently, it is impossible for the mechanical tension servo mechanism known heretofore to operate normally in reverse reproducing mode as well as in the normal recording and/or reproducing mode.
Accordingly, the recording/reproducing apparatuses having reverse reproducing function known heretofore have one motor for rotating the take-up reel shaft and another motor for rotating the supply reel shaft and the tape tension is controlled electrically by controlling the motors. This arrangement is disadvantageous since it makes the recording/reproducing apparatus bulky, increases its weight and raises the cost of production.